The move, first reported by the Washington Post, means Democrats are calling Speaker John Boehner's (R-OH) bluff after his office contended on Monday that a "clean" debt limit increase could not pass the Democratic-led Senate.
Senate leaders intend to begin the process with a vote to proceed to the bill late this week, said one senior aide. The aide said Democratic senators expect to be fully united and will likely need six Republican votes to reach 60 and break an inevitable filibuster.
"We'll be looking to the usual suspects," the aide said.
That's a reference to a contingent of Republicans, led by Sen. John McCain (R-AZ), who have worked with Democrats this year to pass immigration reform, break the logjam on presidential nominees and push for budget negotiations that GOP leaders have blocked.
President Barack Obama strongly supports a clean debt limit increase. Senior White House adviser Dan Pfeiffer said Republicans must decide whether to filibuster and force default.
Boehner has insisted that the House won't raise the debt limit without conservative policy reforms attached, and that Obama's refusal to negotiate is risking default.
"A 'clean' debt limit increase can't pass the Senate, let alone the House," said Boehner spokesman Michael Steel, calling on Democrats to "to step up, act like an adult, and start talking about how we ... deal with the drivers of our debt and deficits."
Senate Majority Leader Harry Reid's (D-NV) spokesman Adam Jentleson asked a Boehner aide on Twitter if the Speaker would permit a vote on a Senate-passed debt limit bill.